Information storage devices are used to retrieve and/or store data in computers and other consumer electronics devices. Energy assisted magnetic recording (EAMR) or heat assisted magnetic recording (HAMR) technology may be used to increase areal density (AD) of hard disks. A laser beam is delivered through an optical target waveguide and excites a near field transducer (NFT) at an air bearing surface (ABS) adjacent the magnetic disk surface. The NFT generates a very strong localized electromagnetic field. When the localized electromagnetic field is close enough to the magnetic recording medium, the recording medium absorbs part of the localized electromagnetic field and heats up in a region limited in part by the small dimension of the NFT. This heating lowers the coercivity of the magnetic medium locally and enables a write pole to magnetize the media with high density, which helps to realize the magnetic recording process with increased AD.
Various methods for focusing the laser to the NFT are known, such as mirror focusing. However, there are deficiencies with the known systems. For example, when using mirror focusing (e.g., parabolic solid immersion mirror), the focus tightness is limited.
There is a need in the art for improved focusing of a laser to an NFT in EAMR/HAMR technology.